Here's their release of how they made it as well. Super interesting read. It's shaders all the way down. http://www.iquilezles.org/www/material/function2009/function...
> With cinematic look, like taken with a real camera. We had some dissagreements here
> • I absolutelly wanted to avoid the CG look - the danish part of the team wanted something sharp and shinny
> • I wanted a hand-held TV camera - they wanted a sts04 like smooth lovely cameras
> • I wanted a realistic scenery - they wanted more action in the scene..
And exploiting impressionism as a compression technique:
> The idea is NOT to render perfect snow, but to draw something that evoques snow, and let the viewer’s brain to trick the viewer.